Impact of physical activity vs high-intensity interval training on autonomic nervous system in young sedentary adults – a pilot study

Objective. This study aimed to evaluate the impact of physical activity versus high-intensity interval training (HIIT) on the cardiac autonomic nervous system in young sedentary adults. Method. This randomized pilot study included sedentary adults aged 18 to 40 years, with less than 600 METs in IPAQ and moderate to severe stress on the Perceived Stress Scale. Twenty-eight participants were randomized into three groups: control, HIIT, and physical activity. The HIIT group underwent 30:30 sec circuit training, while the physical activity group engaged in moderate to vigorous aerobic activities for 12 weeks. The control group received education on the importance of exercise. The primary outcome was cardiac autonomic neuropathy assessed using Ewing’s battery of tests, and the secondary outcome was functional capacity. Result. Significant improvement in cardiac autonomic neuropathy was observed in both the physical activity (p < 0.001) and HIIT groups (p < 0.001), but not in the control group (p = 0.25). Physical activity showed a tendency toward parasympathetic dominance (p = 0.0002), while HIIT showed a tendency toward sympathetic dominance (p = 0.004). Significant improvements in functional capacity were noted in the physical activity (p = 0.002), HIIT (p = 0.001), and control (p = 0.021) groups. Conclusion. Both physical activity and HIIT significantly improve the autonomic nervous system and functional capacity. However, the type of training has varying impact on the autonomic nervous system.